Introduction
A set is a collection of objects, numbers or characters.
{abcdef....wxyz} {1,2,3,4,...45, 46, 47} etc.
Note how the set is enclosed in brackets {.....}
A definite set is one in which all its members are known.
Sets are given uppercase letters: A, B, C, etc.
The elements of sets are given lowercase letters: a, b, c,..etc.
An element x belonging to the set A is written:
A constraint bar {......} is for setting a property that all members satisfy.
A{x l x has the colour blue}  all elements of A are blue
Common Sets
Venn Diagrams
Venn diagrams are used to visualise sets and their relations to one another.
Above is a diagramatic representation of set A. The set can be represented mathematically as: A{1,3,5,7,9} .
Note that set A(the circle) is a subset of the Universal set(the rectangle).
A' (Adash)is called the complement of A. It contains all elements which are not members of A.
A and A' together make up the Universal set.
The union of sets A and B contains all of the elements from both sets.
The intersection of sets A and B contains a particular group of elements that exist in set A and in set B.
Subsets
If B is a subset of A. Then all of the elements of B are also in A.

